Frequently it is desirable to mark or code an article or packaging with various types of information. For example, articles or packaging is provided with marking or coding directed at identifying the product. It is also common to include manufacturing information, such as lot number or manufacturing time or date, etc. Similarly, inventory or other control information may be provided on an article or package. Such markings or coding is typically at least partially variable in nature. Therefore, it may not be advantageous to incorporate such information on a mass printed label or use a stamp or other marking system that does not allow the information to be easily changed.
Various systems have been used in marking or coding articles or packaging. Typically, the marking or coding system is based on a conventional printing operation. For example, in the past, marking and coding systems have been based on screen printing techniques and roller transfer printing. More recently, coding and marking systems have been developed based on inkjet printing and thermal transfer printing.
Even more recently, lasers have been employed in coding and marking systems. According to a general laser marking system, a laser beam is scanned across a target to be marked. The incident energy footprint interacts with the target to produce a change in character. Depending on the application, the change produced by the laser may be visible, e.g. a change in color, or may be a machine detectable change. The information may be human readable text or one of a number of machine readable codes, such as barcodes.
Laser marking systems, in general, may provide several advantages over other marking systems, such as inkjet and thermal transfer marking and coding systems. For example, because laser marking systems do not require contact with the target surface, laser marking and coding systems may be more easily adapted to marking complex target geometries, such as contoured packages. Also laser systems require no consumable component, e.g., ink, and the marks may be permanent.
One drawback of laser marking and coding systems, however, is the relative large size of such systems as compared to inkjet and thermal transfer marking and coding systems. The size of the laser marking or coding system may make it difficult to integrate a laser marking system easily into a production line. Additionally, the large size of a laser marking or coding system, as compared to an inkjet or thermal transfer marking or coding head can make it difficult or impossible to retrofit an inkjet or thermal transfer system with a laser marking unit. Cost is another consideration when comparing laser systems to ink or thermal transfer systems. Laser systems may take a larger share of the product identification market if the initial capital cost of the systems is comparable.